1. Field of the Invention
The present invention relates to a signal processing circuit of an image input apparatus that converts signals in predetermined units arranged in two dimensions, which are obtained usually by an image pickup device in the image input apparatus, such as digital still cameras.
2. Description of the Background Art
Conventionally, image photographed by a digital camera has been subjected to image processing such as rotation, reflection, and conversion of arrangement of color components. At that time, the photographed image data is read in a CPU contained in the digital camera, and the mentioned image processing is conducted in the CPU by software.
Consider now a CPU that has a 32-bit register and thus expresses one pixel of an image data in units of one byte (8 bits) or the like. When this image data is subjected to the mentioned image processing by software, the processing unit of the CPU (32 bits) does not match the unit of pixels (8 bits). Therefore, after the image data is decomposed on a plurality of registers within the CPU, and then rotated, for example, a 32-bit data (hereinafter referred to as “word data”) is reconfigured on the registers. That is, 24 dummy bits are added to an 8-bit image data, to obtain a 32-bit image data. This image data is stored in memory or a storage medium, and then read in the CPU in order to conduct processing. After the processing is completed, the image data is returned to a 8-bit data for preservation. As a result, this processing requires many data conversion processing between a word data and a one-byte data, thereby increasing processing time.